Brahmaputra

(Sanskrit, “son of the god Brahma”), a river in China, India, and Bangladesh. It is known as the Matsang and Tsangpo in Tibet, the Dihang at the irruption through the Himalayas, the Brahmaputra in India, and the Jamuna in Bangladesh. It is 2, 900 km long and its basin area totals 935, 000 sq km. The sources of the Brahmaputra include several rivers that flow down the northern slopes of the Himalayas and the southern slopes of the Kailas Range and join together as one channel near the village of Ombu (at an elevation of approximately 4, 860 m). From this point the Brahmaputra flows parallel to the Himalayas along the bottom of a longitudinal graben of a latitudinal direction for a distance of more than 1, 100 km and receives many tributaries, which are fed mainly by melted snows. Since the slope of the longitudinal graben’s axis is relatively small, the Brahmaputra for the most part flows calmly here and is open to local navigation. Below the mouth of the Giamda River, at approximately 95° ? long., where the Brahmaputra cuts through the spurs of the Tanglha Range and the Himalayas in the deepest of gorges, the river has a turbulent current, numerous rapids, and, in certain places, torrents and cascades. Near the village of Pasighat the Brahmaputra emerges onto the Ganges Plain and flows along the southern foothills of the Himalayas, becoming a huge water artery carrying its peaceful waters along the bottom of a wide valley in a shifting channel that splits up into arms and branches. There are many islands here; Majuli, the largest island, is approximately 70 km long and up to 15 km wide. Bending around the mountains of Assam, the Brahmaputra forms a large bight and then turns southward and flows together with the Ganges. The common channel of the Brahmaputra and Ganges forms an estuary that empties into the Bay of Bengal. The delta of the Ganges and Brahmaputra has an area of more than 80, 000 sq km (the so-called Bengal Delta) and is quite complex in structure. The most important tributaries of the Brahmaputra are the Nau, Chorta Tsangpo, Raka Tsangpo, Kyi Chu, Giamda, Luhit, and Kapili rivers on the left and the Nyang Chu, Subansiri, Kameng, Manas, and Tista rivers on the right.

The Brahmaputra’s water content falls sharply during the winter. It increases when the snow begins to melt in the spring and reaches its peak during the summer as a result of thawing névés and glaciers in the mountains and heavy rains (monsoons) on the Ganges Plain and in the Himalayas. The mean flow rate at the mouth is approximately 12, 000 cu m per sec with the maximum flow rate exceeding 15, 000 cu m per sec (summer) and the minimum measuring 4, 000 cu m per sec (winter). In the lower reaches of the river the water level rises 10-12 m and is often accompanied by flooding. The river’s waters are widely used for irrigation. The Brahmaputra is navigable for a distance of 1, 290 km from the mouth; the river also has boat traffic in certain areas of Tibet. The waterpower potential of the Brahmaputra is great; at the irruption through the Himalayas and below this point it is estimated to be more than 60 million kilowatts. However, the actual energy utilization of the river is small. (Its basin contains the Flower of Light Hydroelectric Power Plant, which was built in 1957 to supply electric power to the city of Lhasa in Tibet.) The major population centers along the Brahmaputra include Shigatse in China and Dibrugarh, Tezpur, Gauhati, and Dhubri in India.